Undiscovered Worlds | Secrets Of The Universe | Spark

[Music] since the dawn of the Space Age we've imagined traveling to worlds beyond our solar system touching down on eerie landscapes and countering alien life-forms what was once science fiction is now becoming science fact [Music] each year we are finding more and more planets around other stars some strange and hostile a few with the potential to harbor life what can we learn about the universe and about our sins [Music] as we scan the galaxy for undiscovered worlds [Music] in the last two decades precision telescopes have allowed us to see into the bright light of distant stars and detect the presence of planets [Music] [Music] this is 51 pegasi a sun-like star about 50 light-years from Earth [Music] in 1995 from slight variations in its light astronomers discovered a planet orbiting around it for the first time in human history we knew for sure that ours is not the only solar system the planet they found is huge more than a hundred times the size of Earth [Music] yet it orbits astonishingly close to its parent star its atmosphere is a scorching 1,300 degrees Celsius [Music] whipping around its star every for Earth days this exoplanet defined everything we thought we knew about solar systems [Music] our solar system began to take shape around in a giant cloud of dust and gas over millions of years time this cloud collapsed and the son was born the cloud flattened into a spinning disk inside dust and rock collided forming the inner planets farther from the Sun hydrogen and helium gas collapsed into dense centers forming the gas giants Jupiter Saturn Uranus and naturally the planet at 51 pegasi known as a hot Jupiter is huddled too close to its parent star to fit this pattern [Music] one theory suggests that it formed far out in the solar nebula but gradually migrated inland [Music] we have much yet to learn about worlds like this but with each new one we discover we move a step closer to understanding planetary systems astronomers found this planet by searching for clues hidden in the light of its parent star the planet exerts a gravitational pull causing the star to wobble slavery at our telescopes the star's light passes through a spectrograph an instrument that breaks the light up into columns like a prison the result is a spectrum that shows patterns of minds characteristic to the star as the star wobbles these lines chef back and forth toward blue as the star comes closer and toward red as the star moves away [Music] today's instruments are so sensitive that they can measure differences in a star's speed as small as one meter per second the speed of a person strolling down the street each waffle represents a complete orbit by the planet around the star based on what they know about gravity astronomers can use this information to estimate the planets mass and its distance from the star that's not the only way to detect these far-off worlds [Music] take the star HD to 0-9 4 5 8 astronomers had already found a hot Jupiter with the wobble method [Music] in 1999 this exoplanet was observed passing in front of its parent star in an event called a transit astronomers noticed that the star's light dipped slightly but regularly every three-and-a-half days this dip in its light was tiny only 1% but it meant that a planet was there making one orbit every 3 and 1/2 Earth days [Music] since larger planets block more starlight astronomers now had a direct way to measure the exoplanet size the planet HD 2 0 9 4 5 8 B turns out to be less massive than Jupiter but it's about 30% larger it is less dense or puffier than any planet in our solar system that discovery led to new techniques for studying an exoplanets atmosphere when the light from the star passes through the atmosphere of the planet the planet's atmosphere imprints upon that light a signature of whatever atoms and molecules are present [Music] in this case instruments aboard the hubble and spitzer space telescope's detected sodium hydrogen methane water vapor and possibly carbon dioxide a collection of molecules that elsewhere might be associated with the presence of life [Music] using transits we have tools that in theory could detect the signatures of life on a rocky earth-like world [Music] from what we know it takes a particular set of chemical building blocks including molecules containing carbon add in a source of energy like a star and liquid water around each star is a so-called habitable zone in which planets are bathed in just the right amount of solar energy for liquid water to flow [Music] where can we look to find planets with solid surfaces and temperatures that allow liquid water to flow [Music] with literally billions of stars in our Milky Way to choose from the possibilities may seem endless but they aren't [Music] supergiant's are the hottest most massive stars they're far too unstable and short-lived and life probably wouldn't have enough time to develop on a planet that orbits they are known to explode in supernovas that would obliterate a planet we can also rule out most double or triple star systems which make up more than half of the galaxy stars with two stars tugging on a single planet its orbit would probably not be stable enough for life to develop [Music] and the vine more storms makes these planets even harder to find what about red dwarfs the most plentiful stars in our galaxy they are smaller and cooler than our Sun but don't emit very much light or heat [Music] still they live far longer than the Sun a red dwarf solar system could survive and evolve over billions of years time in the year 2009 astronomers made their first discovery of a rocky exoplanet orbiting a red dwarf star [Music] called Kuro 7 the world goes around its Sun in just 20 earth hours with surface temperatures at around 2,000 degrees Celsius this extreme world is probably lined with molten rock massive rock EXO planets like Corot 7b known as super Earths are some of the strangest most exotic worlds yet detected [Music] calling it a super-earth doesn't mean it bears much resemblance to our planet most detected so far are simply too close to their central star and too hot for life to survive [Music] there is one newly discovered solar system that may come close [Music] the red dwarf star Gliese 581 is relatively close to Earth at 20 light-years away [Music] a team of French and Swiss astronomers had been studying its light from a telescope in the mountains of Chile they noticed a slight jitter the gravitational tugging of planets they first deduced the presence of Gliese 581 be a planet with 16 times the mass of Earth at a distance from its central star of only six million kilometers it's bound to be very hot then came planet C one and a half times the size of Earth with an orbit of eleven million kilometers its position just inside the life zone means it's probably too hot then there's planet D seven times the mass of Earth at 33 million kilometers from its Sun at the outer edge of the star's habitable zone it receives only 30% of the light that Earth gets from our Sun imagine a much larger version of Mars a planet with a thin atmosphere no liquid water on the surface and temperatures that average around minus 59 degrees Celsius some astronomers suspect that planet D is an icy world that migrated in from the outer solar system [Music] on the other hand what if Planet D possessed some of the attributes of our planet geological activity that produced an atmosphere a moon to stabilize its orbit and a robust magnetic field to shelter it from solar winds in the future as our instruments become more and more sensitive astronomers will look for signs that it has an atmosphere and within it chemical compounds that might be associated with life methane carbon dioxide water vapor it's not out of the question that we or a robotic emissary may one day be able to visit and a closer look it's possible that earth-sized planets maybe even habitable ones are commonplace in our galaxy given the immense distances and the brightness of their parent stars the trick is finding them until recently our technology and methods were best suited to detecting massive planets but that's changing launched in 2009 the Kepler space telescope was designed to look specifically for earth sized planets in the habitable zones of their parent stars Kepler measures light from one hundred thousand stars like the Sun watching for minuscule dips in starlight the tell-tale sign of an exoplanet transit the mission has already discovered an array of giant planets with orbits lasting days or weeks astronomers will be combing their data in the years to come for signs of earth-sized worlds with orbits of a year or more as astronomers continue to comb their data they are finding a remarkable diversity of solar systems kepler-11 at two thousand light-years from Earth has six planets all larger than Earth packed into orbits smaller than that of Venus Kepler 20 has five planets - about the size of Earth but all within the orbit of our merger then there's kepler 47 a double star system with two planets discovered so far the innermost planet the smallest detected by the transit method is three times the size of Earth but it's so close in that it's year is 50 Earth days farther out with an orbit of 303 days planet C is in the life zone of its star unfortunately it's a gas giant a little larger than Neptune we continue to ask are there worlds like ours somewhere out there we now have the technological capability the telescopes and the computers that will begin to help us answer that question whether we find that earth-like planets are commonplace or rare there is one thing we know with certainty our world is but one tiny grain on the beach of a cosmic sea looking in any direction the universe goes on and on for incomprehensible distances [Music] so far billions of years have whispered by the small corner of the galaxy billions of years will transpire after we all are gone [Music] our moment of life is like a breath of air as we look up into the night sky we wonder what new worlds await our discovery and what light will they shed on the origin and evolution of [Music]

Channel: Spark

Views: 244,140

Rating: 4.6553979 out of 5

Keywords: Spark, Science, Technology, Engineering, Learning, How To, education, documentary, factual, mind blown, full documentary, 2017, 2016, 2015, full, space documentary, bbc documentary, Science documentary, Space Documentary, Giant Planets, Are there more planets, What is the biggest star, Biggest Star, astronomy documentary, secrets of the universe, spark universe, secrets of the universe spark, spark documentary, undiscovered world documentary, universe documentary, the universe, spacelive

Id: nRxiRZeGpK4

Length: 24min 27sec (1467 seconds)

Published: Fri Aug 11 2017